Effect of decaffeination conditions on quality parameters of Kangra orthodox black tea

Effect of extraction temperature and pressure on the removal of caffeine from Kangra orthodox black tea using supercritical carbon dioxide was investigated. Maximum caffeine as well as volatile flavor components was extracted at 35 °C/170 bar using 60 g/min flow rate for 90 min extraction in dynamic mode. Satisfactory decaffeination and quality retention were achieved at extraction at 60 °C/90 bar. The quality of extracts reduced at higher extraction temperature and pressure combinations. Maximum amounts of theaflavins (88.88%), thearubigins (81.18%) and catechins (73.53%) were retained at these extraction conditions. Volatile components in original (caffeinated) and decaffeinated black teas were isolated by simultaneous distillation extraction (SDE), and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). 2-Hexenal, 3-hexenol, phenylacetaldehyde, cis-linalool oxide, linalool, trans-geraniol, nerolidol, methyl salicylate, α- and β-ionones decreased in decaffeinated black teas compared to untreated control. β-ionone (1.77%), trans-linalool oxide (5.36%), linalool (7.84%), trans-geraniol (4.32%) and methyl salicylate (1.90%) were retained in satisfactory amount in decaffeination at 60 °C/90 bar. Application of aroma extract dilution analysis revealed 11 odor active compounds with flavor dilution (FD) factor ranging from 8 to 512 and odor quality investigated by GC-FID, GC–MS. Some unknown compounds quantitatively reduced or disappeared during decaffeination process. Although there was considerable loss of theaflavins and thearubigins as well as volatile flavor components, SFE extraction at 60 °C/90 bar for 90 min appears as the method suitable for selective removal of caffeine from the Kangra orthodox black tea

Comparison of headspace analysis of volatile constituents with GC–MS analysis of hydrodistilled and supercritical fluid extracted oil of Capillipedium parviflorum

Volatile constituents of the aerial parts of Capillipedium parviflorum were studied by two different extraction procedures, hydrodistillation (HD), supercritical CO2 extraction (Sc-CO2) and compared with headspace analysis (HS). Sc- CO2 extraction was carried out using nine differential optimization extractions (DOX) at different temperatures (°C) and pressures (MPa), i.e. 35/9, 60/9, 85/9, 35/17, 60/17, 85/17, 35/25, 60/25 and 85/25, to assess the influence on the yield and composition of volatile constituents. In DOX experiments, oil yields varied between 0.01–0.18% and maximum yield (0.18%) was obtained using temperatures and pressures 35/17 and 85/25. The oil is characterized by distinctive presence of very high content of non-terpenes (90.7%) identified in HD oil, 84.0% in Sc-CO2 oil and 92.5% in HS analysis. Monoterpenes were represented in low concentrations in HD oil and were totally absent in Sc- CO2 as well as in HS analysis. Very little variability was observed in the oxygenated monoterpenes in both Sc-CO2 and HD oil representing a low percentage of constituents. Sesquiterpene hydrocarbons were represented between 1.5% and 3.1% in Sc-CO2 extraction, which was higher in comparison with HD and HS techniques. Oxygenated sesquiterpenes were represented in higher percentage in Sc-CO2 than in HD oil and HS analysis. Variability among the major constituents of 4-nonanone, 4-nonanol, 4-undecanone and 4-undecanol was observed in Sc-CO2 extraction carried out under varied temperatures and pressures. Their percentage also varied in HD and HS analysis. 4-Nonanone (2.5%, 60/9 in Sc-CO2; 6.4% in HD and 4.3% in HS), 4-nonanol (21.5% in Sc-CO2, 31.7% in HD and 29.5% in HS), 4-undecanone (33.3%, 85/9 in Sc-CO2; 35.3% in HD and 44.5% in HS) and 4-undecanol (16.5%, 84/17, 60/25 in Sc-CO2; 14.6% in HD and 10.3% in HS) dominated the volatile constituents

Chemical composition of 8 <it>eucalyptus</it> species' essential oils and the evaluation of their antibacterial, antifungal and antiviral activities

<p>Abstract</p> <p>Background</p> <p>In 1957, Tunisia introduced 117 species of <it>Eucalyptus</it>; they have been used as fire wood, for the production of mine wood and to fight erosion. Actually, <it>Eucalyptus</it> essential oil is traditionally used to treat respiratory tract disorders such as pharyngitis, bronchitis, and sinusitis. A few investigations were reported on the biological activities of <it>Eucalyptus</it> oils worldwide. In Tunisia, our previous works conducted in 2010 and 2011 had been the first reports to study the antibacterial activities against reference strains. At that time it was not possible to evaluate their antimicrobial activities against clinical bacterial strains and other pathogens such as virus and fungi.</p> <p>Methods</p> <p>The essential oils of eight <it>Eucalyptus</it> species harvested from the Jbel Abderrahman, Korbous (North East Tunisia) and Souinet arboreta (North of Tunisia) were evaluated for their antimicrobial activities by disc diffusion and microbroth dilution methods against seven bacterial isolates: <it>Haemophilus influenzae</it>, <it>Klebsiella pneumoniae</it>, <it>Pseudomonas aeruginosa</it>, <it>Staphylococcus aureus</it>, <it>Streptococcus agalactiae</it>, <it>Streptococcus pneumoniae</it> and <it>Streptococcus pyogenes</it>. In addition, the bactericidal, fungicidal and the antiviral activities of the tested oils were carried out.</p> <p>Results</p> <p>Twenty five components were identified by GC/FID and GC/MS. These components were used to correlate with the biological activities of the tested oils. The chemical principal component analysis identified three groups, each of them constituted a chemotype. According to the values of zone diameter and percentage of the inhibition (zdi, % I, respectively), four groups and subgroups of bacterial strains and three groups of fungal strains were characterized by their sensitivity levels to <it>Eucalyptus</it> oils. The cytotoxic effect and the antiviral activity varied significantly within <it>Eucalyptus</it> species oils.</p> <p>Conclusions</p> <p><it>E. odorata</it> showed the strongest activity against <it>S. aureus</it>, <it>H. influenzae</it>, <it>S. agalactiae</it>, <it>S. pyogenes</it>, <it>S. pneumoniae</it> and against all the tested fungal strains. In addition, <it>E. odorata</it> oil showed the most cytotoxic effect. However, the best antiviral activity appeared with <it>E. bicostata</it>. Virus pretreatment with <it>E. bicostata</it> essential oil showed better antiviral activity (IC₅₀ = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC₅₀ = 4.8 mg/ml, SI = 3.33). The essential oil of <it>E. astringens</it> showed antiviral activity only when incubated with virus prior to cell infection. This activity was dose-dependent and the antiviral activity diminished with the decreasing essential oil concentration.</p